The present invent ion relates to a process f or recording an image that can be widely applied to a multi-color printer for office use and industrial production of a color filter. More particularly, it relates to a process for recording an image using a photoelectrodeposition method capable of easily forming an image having high colorfulness and high resolution.
In recent years, techniques using an electrodeposition method have been proposed as a process for forming an image that can form a minute image pattern, and have been utilized for printing and producing a color filter. For example, JP-A-6-293125 proposes an offset printing method using an electrodeposition method. JP-A-4-9902 proposes a technique relating to a process for forming a minute pattern utilizing an electrodeposition method. Furthermore, JP-A-5-60914 proposes a technique relating to a process for producing a color filter using an image forming method utilizing an electrodeposition method. However, these methods require that a conductive film on an electrodeposition substrate be previously subjected to patterning by photolithography, which results in a high production cost.
A method containing no photolithography process includes processes for producing a color filter disclosed in JP-A-5-15-157905 and JP-A-5-119209. In these processes for producing a color filter, the conductivity of a light-irradiated part is increased by irradiating with light with utilizing photo-memory properties of a photosemiconductor, and an electrodeposition material is deposited only on the light-irradiated part by utilizing a redox reaction of the elect rodeposition material. This method requires application of a voltage of about 60 V, and it is difficult to control the variations in the thickness of the electrodeposition film. Furthermore, the hysteresis due to the irradiation of light remains on the substrate, which results in low reproducibility.
The present inventors have proposed a process for recording an image utilizing a photoelectromotive force of a photosemiconductor in JP-A-10-97125. According to a method, an electrodeposition material can be deposited by application of a voltage of 5 V or lower, control of the thickness of the electrodeposition film is easily conducted, and a minute image pattern can be formed with good reproducibility. Furthermore, according to a method, because an electrodeposition film formed on a substrate can be transferred as it is to recording paper, no printing plate is necessary, and the method can be preferably applied to a printing machine for office use aiming image recording in small quantity with large variation.
However, in the process for recording an image, because the irradiation of light is conducted from the back surface of a substrate, a material having transparency to the irradiation light must be used as a material of a substrate, a conductive film and a photosemiconductor thin film, and there has been limitation on selection of materials and selection of light sources for irradiation. Furthermore, when the process is applied to a printing machine, there is great restriction on design of the machine because the irradiation of light is conducted from the back surface of the substrate.
An object of the invention is to provide a process for recording an image using a photoelectrodeposition method having high general-purpose property that requires no restriction on the selection of a material used as a substrate.
Another object of the invention is to provide a process for recording an image that can form an image having high resolution and high gradation.
A further object of the invention is to provide a process for producing a color filter of high resolution having a high smoothness and a high light transmissibility.
In order to solve the problems described above, the process for recording an image according to the invention comprises a step of arranging a substrate comprising a support, a conductive film and a photosemiconductor thin film laminated in this order, in such a manner that at least the photosemiconductor thin film comes in contact with an electrodeposition solution; and a step of applying an electric current or a voltage to the conductive film, and simultaneously irradiating the substrate with light from the side of the photosemiconductor thin film through the electrodeposition solution, to generate a photoelectromotive force on a light irradiated part of the photosemiconductor thin film, so as to form an electrodeposition film on the light irradiated part.
When the photosemiconductor thin film is irradiated with light, a photoelectromotive force is generated on the light irradiated part of the photosemiconductor thin film. The photoelectromotive force is added to the bias caused by the electric current or the voltage applied to the conductive film, and when the electric potential of the photosemiconductor thin film exceeds the threshold value required for electrodeposition of the electrodeposition material, an electrodeposition film is formed only on the light irradiated part.
In the invention, because the irradiation of light is conducted from the side of the photosemiconductor thin film through thee electrodeposition solution, it is not necessary that the support and the conductive film which constitute the substrate are transparent to the irradiated light. Therefore, the range of selection of the light source used for irradiation of light and the materials used in the substrate are widened. Furthermore, because the irradiation of light is conducted from the side of the photosemiconductor thin film, the restriction on design of printing machines is also dispelled.
By using an ionic molecule, whose solubility changes corresponding to the change of the pH, as the electrodeposition material used in the invention, the electric current or the voltage applied to the conductive film can be set small. As a result, the thickness of the electrodeposition film can be controlled with high precision, and thus an image having a high smoothness can be formed with good reproducibility.
Furthermore, by repeating the process described above by using various kinds of electrodeposition solutions, a multicolor image can be formed on a substrate. When a red electrodeposition film, a green electrodeposition film and a blue electrodeposition film are formed according to the process for forming an image of the invention, and then a black electrodeposition film is formed on the part on which the electrodeposition films are not formed, a color filter containing a black matrix can be easily produced without using photolithography.
Furthermore, because the electrodeposition film formed on the substrate can be easily transferred to various image retaining substrates, the process for recording an image can be widely applied to various fields, such as a printing process of ordinary paper and industrial production of a color filter.